Sucker rod coupling



Aug. 17, 1965 R. B. MERIPOL SUCKER ROD COUPLING 2 Sheets-Sheet L Filed Jan. 9, 1964 FIG.I

INVENTOR ROBERT B. MERIPOL FIG.6

AT TOR N EYS 1965 R. B. MERIPOL 3,201,158

SUGKER ROD COUPLING Filed Jan. 9, 1964 2 Sheets-Sheet 2 INVENTOR. ROBERT B MERIPOL ATTORNEYS United States Patent C 3,201,158 SUCKER RUB COUPLING Robert B. Meripol, Fort Worth, Tex., assignor to Liberty Manufacturing Co. of Texas, Fort Worth, Tex., a corporation of Texas Filed Jan. 9, 1964, Ser. No. 336,741 7 Claims. (Cl. 287-117) This invention relates to sucker rod couplings for oil Wells. More particularly, the invention relates to a coupling design which retain-s the benefits of the American Petroleum Institute standard through-tapped sucker rod coupling, but in a manner obtains the benefits of a solid center coupling. Still more particularly, the invention relates to a device insertable in a through-tapped sucker rod coupling by which the benefits of a solid center cou pling are obtained.

Oils wells often require a bottom-hole pump in order to bring crude oil to the surface. The most common met-hurl of actuating bottom-hole pumps includes the use of a string of rods, usually termed sucker rods.

Sucker rods. are of practical length, usually to feet long each, and are joined together with couplings called: Sucker rod couplings.

The string. of rods held together by the couplings is connected to the pump at the bottom of the well bore and on the surface is connected to a pumping unit which sets up a reciprocating action, thus actuates the pump.

Under such reciprocation, the string of rods tend to stretch on the upstroke and under adverse operating conditions, such as parafiinic accumulations in the well bore or too high reciprocation rate or other cause, portions of the string will be under compression. In time, stress and fatigue cause failure in the rod string whether from normal or abnormal operating conditions. Failure will occur in some part of a rod or in the sucker rod coupling.

Failure in the rod string causes an expensive well bore service job.

If well bore service jobs can be reduced, a substantial savings can be realized in operation costs, plus the benefit of decreased loss of crude oil'production due to shutdowns.

The scope of this invention is centered on extending the life of the sucker rod couplings, thus reducing the number of well bore service jobs attributable to sucker rod cou pling failures of present popular design.

To better understand the objectives of the invention, a more complete description of the sucker rod string will be helpful.

The standard through-tapped sucker rod coupling has become an industry standard for two outstanding reasons: (1) Best possible alignment of sucker rods is guaranteed when two rods are joined by threaded attachment within the continuously threaded coupling; and, (2) A continuous thread is obtained by a single machining operation on tubular coupling material, thus manufacturing costs are at a minimum.

Another industry standard, relative to sucker rods, has; been settled upon whereby the length of the threaded ends of the sucker rods is established. When the aforementioned threaded ends are engaged fully within the industry standard sucker rod coupling, the rod ends do not meet one another; a space is left.

To the extent that steel will stretch, is elastic, and will fail beyond its elastic or fatigue limits, one can liken the sucker rod coupling to a piece of rubber tube one inch in diameter and four inches long. Now, place in each end of the rubber tube a short wooden plug, leaving an inch or more gap at thecenter of the tube; grasp both ends of the tube about the wooden plug and stretch tubethe rubber maximum necking down at the center.

3,2ll.,l5.8 Patented Aug. 17, 1965.

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Now substituting the sucker rod coupling for the tube and sucker rod threaded ends for the wooden plugs, as the rod string is stressed and unstressed the center sections of the rod couplings are similarly stressed to the rubber tube, with maximum coupling stress occurring at the first unsupported thread of the coupling beyond the rod thread ends.

If the center section of the sucker rod coupling is made solid, substantially, the stress in the coupling is distributed more uniformly throughout its length and stress at the rod ends is reduced accordingly.

It is a principal object of this invention to retain the benefits of the present industry standard sucker rod couplings, i.e., best possible alignment throughout the length of the coupling and economical manufacturing costs, yet afford the advantages of a strong center portion coupling, by providing an insert therefor.

Another objective is to provide an insert that may be installed within the sucker rod coupling at time of manufacture of the coupling, and in couplings held in warehouse stock, and at time of well service job in couplings in use in the well bore.

Another objective of this invention is to provide a tool that can be used to advance the insert to the center portion of the rod coupling and hold it steady while making the insert immobile at the point.

The invention contemplates an insert for a sucker rod coupling having an expandable externally and internally threaded tubular member threadably insertable in said coupling; and a. truncated conical externally threaded expander member with tool receiving means in one end thereof, said expander insertable in said tubular member.

The invention further contemplates a. sucker rod coupling having inserted therein the abovementioned insert.

The invention further contemplates a tool to advance the insert to the center point of the coupling, and no further, as gauged by the body length of the tool, and upon reaching the center point of the coupling the key portion of the tool holds the insert temporarily immobile in cooperation with the handles of tool until an auxiliary tool advances the expander member of the insert to accomplish permanent immobility of the insert.

Other objects, and advantages of the present invention will become readily apparent from the following detailed description of the invention with specific references to the accompanying drawings which:

FIGURE 1 illustrates the industry standard sucker rod coupling in cross section with sucker. rods in place at.

, FIGURE 6 illustrates the cross-section taken at 6-6 of FIGURE 4 of the straight thread portion and tapered thread portion relationshipof the preferred expandable member of the insert.

FIGURES 7 and 9 illustrate obvious alternates to;

FIGURE 4.

FIGURE 8 illustrates one obvious alternate employing a plurality of rigid hinges. 1 l

FIGURE 10 illustrates one obvious alternate to FIG- URE 5 when the expandable member of the insert has no internal threads. i

In describing the preferred embodiment of the invention illustrated in the drawing, specific terminology will be resorted to for the sake of clarity. However, it is a not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in similar manner to accomplish a similar purpose.

The well bore is omitted from the illustrations as are the bottom hole pump and surface pumping unit.

FIGURE 1 illustrates one of many rod-and-coupling connections in any oil Well bore Where such are employed with numeral 1i) denoting the sucker rods having wrench square portions 12, threaded pins 14 and pin collars 16.

Pins 14 are threadably engaged in sucker rod coupling body 18 having continuous internal threads 20.

The connection of sucker rods with sucker rod coupling 18 is made secure by Wrenches applied to Wrench squares 12, as in a couple, and then exert suitable force. Pin collars 16 are then tightly engaged with sucker rod coupling body 18. The ends of threaded pins 14 are separated by chamber 22.

Within chamber 22, the insert comprising the expandable tubular member 24 and its cooperative expander member 26 will be positioned, or any mechanical equivalent such as expandable tubular members illustrated in FIGURES 7, 8, and 9 with cooperative expander member such as FIGURES 5 and 10.

Preferred insert expandable tubular member 24 in FIGURE 4 is a tubular piece having segmentation 28. Segmentation is to include a single cutting through of the tubular wall as in FIGURES 4 and 7 and a plurality of through-cuts of the wall as suggested in FIGURE 9. The means to hold the pieces of a plurality segmented expandable member together as one piece until insertion in the coupling, can be accomplished with cement and other practical means.

Preferred insert expandable tubular member 24 in FIG- URE 4 has a rigid hinge portion 30. The hinge is accomplished by a partial through-cut of the tubular wall, beginning the cut from the exterior of the tubular piece, at a place opposite segmentation 28 and the cut extending from end to end of the tubular piece. The expandable member 24 may have a pluarlity of rigid hinges as suggested in FIGURE 8 and without segmentation 28.

Insert expandable member 24 has external thread 32 that is threadably insertable within threads of the sucker rod coupling body 18.

Preferred insert expandable tubular member 24 in FIGURE 4 has tapered internal thread 34 as illustrated further in FIGURE 6. However, a functional expandable tubular member can be made having straight internal threads or no threads at all as suggested in FIG- URES 7, 8, and 9.

Preferred insert expandable tubular member 24 in FIGURE 4 has the preferred truncated conical expander member 26 of FIGURE 5 with external threads 36 threadably insertable within threads 34. Said expander member 26 of FIGURE 5 has tool receiving means 38 in one end thereof. Should the expander member 26 of FIG URE 10 be employed, it may be desirable to employ a tubular expandable member 24 without internal thread, having in mind drive-setting the expander member 26 of FIGURE 10. Tool 40 has tubular body 42 with inside diameter larger than the largest diameter of expander member 26 and smaller in diameter than the inside diameter of sucker rod coupling body 18. The tool body length from beneath handles 44 to transverse tubular surface 46 is suitable to advance expandable member 24 to chamber 22 within sucker rod coupling body 18, when handles 44 contact one end of coupling body 18. Tool 40 has engaging key 48 which extends beyond tool tubular body 42, that is insertable in the opening of segmentation 28 or the opening adjacent to a rigid hinge portion 30. Tool 40 may have engaging keys. Auxiliary tool 50 is one like an Allen wrench when preferred expander member 26 of FIGURE 5 is employed, or a driving pin when e p r member 2 0 FIG RE .10 is employed.

The steps necessary to assemble the preferred embodiment of the invention are obvious:

First, by hand engage threads 36 of expander member 26 within threads 34 of expandable member 24 to reach a snug fit;

Next, engage threads 32 of expandable member 24 within threads 20 of sucker rod body 18 and advance the expandable member 24 towards chamber 22 in body 18, by hand;

Next, engage key 43 of tool 40 within the opening of segmentation 28 and continue the advancement of expandable member 24 until the handles 44 of tool 40 touch n end of body 18, thereby positioning the insert for sucker rod coupling within chamber 22;

Next, insert auxiliary tool 50 into tool receiving means 38 in the face of expander member 26;

Lastly, create a force couple by applying an advancing force on auxiliary tool 50 and a backup force on handles 44 of such magnitude to accomplish permanent immobility of the expandable member 24.

Although this invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made only by Way of example and that numerous changes in the details of construction, combination and arrangement of parts may be resorted to Without departing from the spirit and scope of the invention as hereinafter claimed.

I claim:

1. A sucker rod coupling having improved tension distortion resistance comprising:

a body member of tubular configuration having continuous internal threads substantiallyrthe full length of the internal Wall thereof, with unthreaded portions at each end, the body member having parallel planor opposed ends;

an externally threaded tubular member threadably positioned Within the tubular body member-intermediate the ends thereof, the tubular member being of short axial length relative to the body member leaving sucker rod receiving body threads to either side thereof, the tubular member having at leastone slit in the wall thereof whereby the tubular member is radially externally expandable; and

an expander member of length substantially equal the length of the tubular member, the expander member forceably positionable in the tubular member to radially expand the tubular member against the internal wall of the body member to reinforce the deformation resistance of the intermediate portion of the body member.

2. A sucker rod coupling according to claim 1 wherein the tubular member has tapered internal threads therein and wherein the expander member has tapered external threads thereon whereby the expander member is threadable into the tubular member to cause radial expansion of the tubular member against the internal wall of the body member.

3. A sucker rod coupling according to claim 1 wherein the tubular member has a smooth tapered axial internal opening therein and wherein the expander member has a smooth tapered external surface whereby the expander member may be forced into the tapered opening in the tubular member to cause radial expansion of the tubular member against the internal wall of the body member.

4. A sucker rod coupling according to claim 1 wherein the tubular member has a single slit in the wall thereof and a hinge forming notch in the surface of the exterior wall thereof opposite the said slit whereby said tubular member is increasingly externally expandable.

5. A sucker rod coupling having improved tension distortion resistance comprising:

a body member of tubular configuration having continuous internal threads substantially the full length of the internal Wall thereof with unthreaded portions at each end, the body member having parallel planor opposed ends;

an externally threaded tubular member threadably positioned within the tubular body member intermediate the ends thereof leaving sucker rod receiving body threads to either side thereof, the tubular member being of short axial length relative to the body member, the tubular member having a plurality of spaced radial notches in the surface of the exterior wall thereof whereby the tubular member is radially ex- 1 ternally expandable; and an expander member of length substantially equal the length of the tubular member, the expander member forceably positionable in the tubular member to radially expand the tubular member against the internal wall of the body member to reinforce the deformation resistance of the intermediate portion of the body member. l 6. A sucker rod coupling according to claim 5 wherein the tubular member has tapered internal threads therein and wherein the expander member has tapered external threads thereon whereby the expander member is threadable into the tubular member to cause radial expansion of the tubular member against the internal wall of the body member.

7. A sucker rod coupling according to claim 5 wherein the tubular member has a smooth tapered axially internal opening therein and wherein the expander member has a smooth tapered external surface whereby the expander member be forced into the tapered opening in the tubular member to cause radial expansion of the tubular member against the internal wall of the body member.

References Cited by the Examiner UNITED STATES PATENTS 595,437 12/97 Greenfield 285-383 X 668,017 2/01 Pessano 287-114 941,355 11/09 Bostian 285-323 X 1,158,085 10/15 Tennyson 81-71 1,588,128 6/26 Montgomery 287-117 X 1,599,270 9/26 Axelson 287-117 1,822,444 9/31 MacClatchie 285-338 2,487,241 11/49 Hilton 285-383 X 2,508,409 5/50 Lord 287-125 2,619,861 12/52 Wanamaker 81-121 2,622,120 12/52 Knasco et a1 287-125 2,827,925 3/58 Meibaum 287-117 X FOREIGN PATENTS 231,098 3/25 Great Britain. 365,375 1/ 32 Great Britain.

CARL W. TOMLIN, Primary Examiner. 

1. A SUCKER ROD COUPLING HAVING IMPROVED TENSION DISTORTION RESISTANCE COMPRISING: A BODY MEMBER OF TUBULAR CONFIGURATION HAVING CONTINUOUS INTERNAL THREADS SUBSTANTIALLY THE FULL LENGTH OF THE INTERNAL WALL THEREOF, WITH UNTHREADED PORTIONS AT EACN END, THE BODY MEMBER HAVING PARALLEL PLANOR OPPOSED ENDS; AN EXTERNALLY THREADED TUBULAR MEMBER THREADABLY POSITIONED WITHIN THE TUBULAR BODY MEMBER INTERMEDIATE THE ENDS THEREOF, THE TUBULAR MEMBER BEING OF SHORT AXIAL LENGTH RELATIVE TO THE BODY MEMBER LEAVING SUCKER ROD RECEIVING BODY THREADS TO EITHER SIDE THEREOF, THE TUBULAR MEMBER HAVING AT LEAST ONE SLIT IN THE WALL THEREOF WHEREBY THE TUBULAR MEMBER IS RADIALLY EXTERNALLY EXPANDABLE; AND AN EXPANDER MEMBER OF LENGTH SUBSTANTIALLY EQUAL THE LENGTH OF THE TUBULAR MEMBER, THE EXPANDER MEMBER FORCEABLY POSITIONABLE IN THE TUBULAR MEMBER TO RADIALLY EXPAND THE TUBULAR MEMBER AGAINST THE INTERNAL WALL OF THE BODY MEMBER TO REINFORCE THE DEFORMATION RESISTANCE OF THE INTERMEDIATE PORTION OF THE BODY MEMBER. 